feat(experimentation): expose experiment rollout in API responses

api/experimentation/serializers.py

@@ -19,7 +19,10 @@
     WarehouseConnection,
     WarehouseType,
 )
-from experimentation.services import apply_experiment_rollout
+from experimentation.services import (
+    apply_experiment_rollout,
+    get_experiment_rollout,
+)
 from experimentation.types import (
     SNOWFLAKE_DEFAULTS,
     MetricExperimentResult,
@@ -251,7 +254,9 @@ class ExperimentSerializer(serializers.ModelSerializer):  # type: ignore[type-ar
         required=False,
         write_only=True,
     )
-    experiment_rollout = ExperimentRolloutSerializer(required=False, write_only=True)
+    experiment_rollout: Any = ExperimentRolloutSerializer(
+        required=False, write_only=True
+    )
 
     class Meta:
         model = Experiment
@@ -395,6 +400,13 @@ class ExperimentListSerializer(ExperimentSerializer):
     )
 
 
+class ExperimentDetailSerializer(ExperimentListSerializer):
+    experiment_rollout = serializers.SerializerMethodField()
+
+    def get_experiment_rollout(self, experiment: Experiment) -> dict[str, Any] | None:
+        return get_experiment_rollout(experiment)
+
+
 class ExperimentExposuresSerializer(serializers.ModelSerializer):  # type: ignore[type-arg]
     is_final = serializers.BooleanField(read_only=True)
 

api/experimentation/services.py

@@ -54,11 +54,14 @@
     srm_p_value,
 )
 from features.models import FeatureState
+from features.value_types import BOOLEAN, INTEGER, STRING
 from features.versioning.dataclasses import FlagChangeSet
 from features.versioning.versioning_service import update_flag
 from integrations.flagsmith.client import get_openfeature_client
 from segments.models import Condition, Segment, SegmentRule
 
+_ROLLOUT_VALUE_TYPE = {INTEGER: "integer", STRING: "string", BOOLEAN: "boolean"}
+
 if typing.TYPE_CHECKING:
     from collections.abc import Sequence
     from datetime import datetime
@@ -592,6 +595,42 @@ def apply_experiment_rollout(experiment: Experiment, spec: RolloutSpec) -> None:
         )
 
 
+def get_experiment_rollout(experiment: Experiment) -> dict[str, typing.Any] | None:
+    segment_id = experiment.rollout_segment_id
+    if segment_id is None:
+        return None
+
+    feature_state = FeatureState.objects.get_live_feature_states(
+        environment=experiment.environment,
+        additional_filters=Q(
+            feature_segment__segment_id=segment_id, identity__isnull=True
+        ),
+        feature_id=experiment.feature_id,
+    ).latest("id")
+
+    condition = Condition.objects.get(
+        rule__segment_id=segment_id, operator=PERCENTAGE_SPLIT
+    )
+    value = feature_state.feature_state_value
+    return {
+        "enabled": feature_state.enabled,
+        "rollout_percentage": float(condition.value or 0),
+        "feature_state_value": {
+            "type": _ROLLOUT_VALUE_TYPE.get(value.type or STRING, "string"),
+            "value": (
+                str(value.value).lower() if value.type == BOOLEAN else str(value.value)
+            ),
+        },
+        "multivariate_feature_state_values": [
+            {
+                "multivariate_feature_option": mv.multivariate_feature_option_id,
+                "percentage_allocation": mv.percentage_allocation,
+            }
+            for mv in feature_state.multivariate_feature_state_values.all()
+        ],
+    }
+
+
 def mark_warehouse_pending_connection(
     connection: WarehouseConnection,
 ) -> WarehouseConnection:

api/experimentation/views.py

@@ -38,6 +38,7 @@
     WarehouseConnectionPermission,
 )
 from experimentation.serializers import (
+    ExperimentDetailSerializer,
     ExperimentExposuresSerializer,
     ExperimentListSerializer,
     ExperimentMetricSerializer,
@@ -178,7 +179,9 @@ def get_serializer_context(self) -> dict[str, Any]:
         return context
 
     def get_serializer_class(self) -> type[BaseSerializer[Experiment]]:
-        if self.action in ("list", "retrieve", "start", "pause", "complete", "rollout"):
+        if self.action == "retrieve":
+            return ExperimentDetailSerializer
+        if self.action in ("list", "start", "pause", "complete", "rollout"):
             return ExperimentListSerializer
         return ExperimentSerializer
 

api/tests/unit/experimentation/test_experiment_views.py

@@ -2013,3 +2013,46 @@ def test_patch__experiment_rollout_on_update__returns_400(
     # Then
     assert response.status_code == status.HTTP_400_BAD_REQUEST
     assert "Cannot change the rollout" in str(response.json())
+
+
+def test_get_detail__with_rollout__returns_rollout(
+    admin_client_new: APIClient,
+    environment: Environment,
+    experiment_with_rollout: Experiment,
+    multivariate_options: list[MultivariateFeatureOption],
+    enable_features: EnableFeaturesFixture,
+) -> None:
+    # Given
+    enable_features(EXPERIMENT_FLAG)
+    option_a, option_b, _ = multivariate_options
+
+    # When
+    response = admin_client_new.get(_detail_url(environment, experiment_with_rollout))
+
+    # Then
+    assert response.status_code == status.HTTP_200_OK
+    rollout = response.json()["experiment_rollout"]
+    assert rollout["enabled"] is True
+    assert rollout["rollout_percentage"] == 20.0
+    assert rollout["feature_state_value"] == {"type": "string", "value": "control"}
+    assert {
+        (mv["multivariate_feature_option"], mv["percentage_allocation"])
+        for mv in rollout["multivariate_feature_state_values"]
+    } == {(option_a.id, 50.0), (option_b.id, 50.0)}
+
+
+def test_get_detail__without_rollout__returns_null(
+    admin_client_new: APIClient,
+    environment: Environment,
+    experiment: Experiment,
+    enable_features: EnableFeaturesFixture,
+) -> None:
+    # Given
+    enable_features(EXPERIMENT_FLAG)
+
+    # When
+    response = admin_client_new.get(_detail_url(environment, experiment))
+
+    # Then
+    assert response.status_code == status.HTTP_200_OK
+    assert response.json()["experiment_rollout"] is None

api/tests/unit/experimentation/test_services.py

@@ -1478,3 +1478,99 @@ def test_apply_experiment_rollout__update_flag_fails__rolls_back(
         rule__segment=experiment.rollout_segment, operator=PERCENTAGE_SPLIT
     )
     assert condition.value == "20.0"
+
+
+def test_get_experiment_rollout__rollout_exists__returns_representation(
+    experiment_with_rollout: Experiment,
+    multivariate_options: list[MultivariateFeatureOption],
+) -> None:
+    # Given a rollout (20%, options split 50/50, value "control") from the fixture
+    option_a, option_b, _ = multivariate_options
+
+    # When
+    rollout = services.get_experiment_rollout(experiment_with_rollout)
+
+    # Then
+    assert rollout is not None
+    assert rollout["enabled"] is True
+    assert rollout["rollout_percentage"] == 20.0
+    assert rollout["feature_state_value"] == {"type": "string", "value": "control"}
+    assert {
+        (mv["multivariate_feature_option"], mv["percentage_allocation"])
+        for mv in rollout["multivariate_feature_state_values"]
+    } == {(option_a.id, 50.0), (option_b.id, 50.0)}
+
+
+def test_get_experiment_rollout__no_rollout__returns_none(
+    experiment: Experiment,
+) -> None:
+    # Given an experiment without a rollout
+    # When / Then
+    assert services.get_experiment_rollout(experiment) is None
+
+
+def test_get_experiment_rollout__v2_versioning__returns_representation(
+    environment_v2_versioning: Environment,
+    multivariate_feature: Feature,
+    multivariate_options: list[MultivariateFeatureOption],
+    admin_user: FFAdminUser,
+) -> None:
+    # Given a rollout on a v2 environment
+    option_a, option_b, _ = multivariate_options
+    experiment = Experiment.objects.create(
+        environment=environment_v2_versioning,
+        feature=multivariate_feature,
+        name="exp",
+        hypothesis="h",
+        status=ExperimentStatus.CREATED,
+    )
+    services.apply_experiment_rollout(
+        experiment,
+        RolloutSpec(
+            enabled=True,
+            rollout_percentage=30.0,
+            feature_state_value="control",
+            value_type="string",
+            multivariate_values=[
+                MultivariateValueChangeSet(option_a.id, 60.0),
+                MultivariateValueChangeSet(option_b.id, 40.0),
+            ],
+            author=AuthorData(user=admin_user),
+        ),
+    )
+
+    # When
+    rollout = services.get_experiment_rollout(experiment)
+
+    # Then
+    assert rollout is not None
+    assert rollout["rollout_percentage"] == 30.0
+    assert {
+        (mv["multivariate_feature_option"], mv["percentage_allocation"])
+        for mv in rollout["multivariate_feature_state_values"]
+    } == {(option_a.id, 60.0), (option_b.id, 40.0)}
+
+
+def test_get_experiment_rollout__boolean_value__returns_lowercase_string(
+    experiment: Experiment,
+    admin_user: FFAdminUser,
+) -> None:
+    # Given
+    services.apply_experiment_rollout(
+        experiment,
+        RolloutSpec(
+            enabled=True,
+            rollout_percentage=20.0,
+            feature_state_value="true",
+            value_type="boolean",
+            multivariate_values=[],
+            author=AuthorData(user=admin_user),
+        ),
+    )
+
+    # When
+    rollout = services.get_experiment_rollout(experiment)
+
+    # Then
+    assert rollout is not None
+    assert rollout["feature_state_value"] == {"type": "boolean", "value": "true"}

docs/docs/deployment-self-hosting/observability/_events-catalogue.md

@@ -476,7 +476,7 @@ Attributes:
 ### `warehouse.connection.connected`
 
 Logged at `info` from:
- - `api/experimentation/services.py:625`
+ - `api/experimentation/services.py:664`
 
 Attributes:
  - `environment.id`
@@ -485,7 +485,7 @@ Attributes:
 ### `warehouse.connection.test_event_sent`
 
 Logged at `info` from:
- - `api/experimentation/services.py:605`
+ - `api/experimentation/services.py:644`
 
 Attributes:
  - `environment.id`
@@ -494,7 +494,7 @@ Attributes:
 ### `warehouse.srm.overallocated`
 
 Logged at `error` from:
- - `api/experimentation/services.py:388`
+ - `api/experimentation/services.py:391`
 
 Attributes:
  - `environment.id`
@@ -504,7 +504,7 @@ Attributes:
 ### `warehouse.srm.unkeyed_variant`
 
 Logged at `error` from:
- - `api/experimentation/services.py:374`
+ - `api/experimentation/services.py:377`
 
 Attributes:
  - `environment.id`